Proposed Propeller AD To Affect T-34 And Navion Owners 

As previously reported in an ANN Daily News Report and an accompanyingAero-Cast Special Feature, EAA is weighing in on a recently proposed airworthiness directive (AD) that would affect T-34 and Navion aircraft equipped with McCauley propellers. The proposed AD comes as a result of tests conducted by McCauley, which identified a high-stress condition that reduces the fatigue life and damage tolerance of propellers when installed with certain engines.

The stress condition, if left unaddressed, could result in blade or hub failure and result in separation of a propeller blade and subsequent loss of control of the airplane.

The proposed AD only affects aircraft with McCauley model 3A32C406/82NDB-X and D3A32C409/82NDB-X propellers installed on Teledyne Continental IO-520, TSIO-520, or IO-550 engines.

The FAA estimates the AD would affect about 2,350 aircraft, and would add an rpm restriction on continuous propeller operation between 2,350 and 2,450 rpm at 24 inches Hg and higher manifold pressure.

Repetitive propeller blade inspection would also be required, and a 10,000-hour life limit on the propeller would be imposed when installed with the noted engines.

EAA members are encouraged to submit their comments or questions regarding the AD to Timothy Smyth, Aerospace Engineer, Chicago Aircraft Office (see link).

FMI: http://dmses.dot.gov/docimages/pdf94/371124_web.pdf